1. Field of the Invention
This invention generally relates to a ball-splined shaft assembly suitable for use in industrial robots, particularly in arm sections thereof, and, in particular, to a ball-splined shaft assembly having a driving mechanism so that its shaft may be driven to rotate as well as to feed.
2. Description of the Prior Art
A typical prior art ball-splined shaft assembly having a driving mechanism is illustrated in Pat. Laid-open Pub. No. 62-165057, in which grooves for a ball screw are formed in a ball-splined shaft and an outer cylinder of the ball screw and the driving mechanism (motor) are integrated to move the ball-splined shaft. With such a structure, however, the ball screw and the driving mechanism are mounted in a line along the longitudinal direction in order to limit the size in the radial direction, so that the size in the longitudinal direction necessarily tends to become larger. Besides, it requires an increased number of parts which tend to make its manufacture difficult and thus pushes up the cost. In addition, the linear motion accuracy tends to be impaired.